Observations of the Fall Breakdown of Stratification on the Mid Atlantic Bight Shelf

In the fall, the coastal ocean over the Mid Atlantic Bight (MAB), the southern half especially, transitions from one of the most highly stratified oceanographic systems to completely unstratified, necessitating an unusually large seasonal buoyancy loss. In October and November of 2015, we observed the fall breakdown of stratification over the shelf just north of Cape Hatteras with a combination of ship and AUV glider-based observations, collecting observations of in situ stratification and turbulent mixing, as well as surface buoyancy fluxes, as part of the ONR-sponsored CASPER project. Using these observations, we characterize the fall breakdown, detailing episodic destratifying events associated with passing storms and comparing the relative impacts of surface buoyancy loss, in situ tubulent mixing and advective buoyancy loss. We also investigate the relative roles of wind driven mixing of the surface boundary layer, tidally driven mixing and mixing associated with near inertial motions.